基于基底膜响应的圆窗激振性能评估偏差研究

Evaluation Deviation of Round-Window Stimulation Based on Basilar Membrane Response

目的研究采用传统基底膜位移评价标准评估圆窗激振式人工中耳听力补偿性能的准确性,为圆窗激振式人工中耳的性能评估提供理论基础。方法基于耳蜗几何结构的实验数据,建立耳蜗感声微观有限元模型,通过对比内听毛细胞、外听毛细胞、盖膜等部位位移响应的实验测量值,验证模型的可靠性。基于该模型,对比分析正向激振、圆窗激振下的基底膜位移与内听毛细胞静纤毛剪切位移;以内听毛细胞静纤毛剪切位移作为感声标准,研究圆窗激振时采用传统人工中耳基底膜评价标准的等效声压级偏差。结果在所研究耳蜗微段对应的5 k Hz特征频率处,相同幅值的声压作用下,圆窗激振的基底膜位移和内听毛细胞静纤毛剪切位移均小于正向激振的对应值。结论正向激振下的内听毛细胞更兴奋,感声效果更强。同时,采用正向激振的基底膜位移评价方法评估圆窗激振的听力补偿效果,会高估圆窗激振的听力补偿性能;但偏差较小,是一种相对可靠的评价方法。

Objective To study the accuracy of traditional basilar membrane displacement evaluation criteria for evaluating hearing compensation performance of round window-stimulated middle ear implant,so as to provide the theoretical basis for performance evaluation of round window-stimulated middle ear implant.Methods An acoustic microscopic finite element model of cochlea was constructed based on experimental data of the cochlea geometry.Reliability of this model was verified by comparison with experimental measurement values of inner hair cell,outer hair cell,tectorial membrane displacement.Based on this model,the displacement of basilar membrane and the stereocilia shear displacement of inner hair cells under forward stimulation and round-window stimulation were comparatively analyzed.Using the stereocilia shear displacement of inner hair cells as the criterion for sense of sound,the equivalent sound pressure level(SPL)deviation under round-window stimulation was studied when using traditional basilar membrane displacement as evaluation criterion.Results At 5 k Hz characteristic frequency of the studied slice of cochlea,under sound pressures with the same amplitude,the displacement of basilar membrane and the stereocilia shear displacement of inner hair cells under round-window stimulation were lower than that under forward stimulation.Conclusions Under forward stimulation,the inner hair cells were more excited and the performance for sense of sound was better than that under round-window stimulation.Concurrently,using the displacement of basilar membrane under forward stimulation as the criterion of hearing compensation performance would overestimate hearing compensation performance of middle ear implant under round-window stimulation;but the deviation was relatively small,which was a relatively reliable evaluation method.